A shoe generally consists of two basic parts, an upper and a sole. The upper, which is attached to the sole, is generally designed to encase the top and sides of the foot, with the sole encasing and cushioning the bottom of the foot. Both the upper and the sole secure the shoe to the foot and provide support and protection. The sole provides additional protection, stability and cushioning to the foot, as well as aiding in the overall durability of the shoe.
The soles of modern footwear are often comprised of three separate components; the insole, midsole, and outsole, each lending desirable properties to the overall sole. In some instances, most notably where a reduction in weight is desirable, separate sole components can be combined or omitted.
Modern soles often comprised ethylene vinyl acetate copolymer (“EVA”) or dual-density EVA. EVA is lightweight foam based cushioning. Dual-Density EVA is firmer and heavier (twice the mass in the same amount of space) but still a foam-based cushioning.
The insole component is often comprised of a thin layer of EVA, and is the portion of the sole in direct contact with the foot.
The outsole component is that portion of the sole which directly impacts the walking or running surface and generally must be highly durable. The outsole is often comprised of carbon rubber (which is hard), or blown rubber (which is softer). In some instances, the outsole component can be comprised of EVA. In addition, a combination of various materials can be used to produce outsoles with different textures and properties.
It is desirable to have an outsole that is comfortable, responsive and durable with the right mix of bounce and cushion. The foot undergoes significant stress when walking, running, jumping, stopping and starting. The outsole is a very significant and important component in any shoe. There have been many attempts over the years to improve the qualities of an outsole.
The midsole component is often designed to achieve a balance between performance, comfort, looks and durability. The midsole acts as the “shock absorber” between the outsole and the insole. Modern midsoles are typically fashioned from EVA or polyurethane.
In some instances, normally when lightweight is desirable, the outsole and the midsole are combined into a single combined sole component. In this configuration the midsole and outsole are comprised of the same material. This type of combined sole is often constructed from EVA or other materials that exhibit desirable properties. A combined sole provides for a significantly lighter sole (and thus a lighter weight shoe) and also reduces manufacturing complexity.
However, until now, there have been drawbacks to combined soles. Current combined soles are lacking in durability and longevity as compared to soles comprised of a separate midsoles and an outsoles made of rubber. The lack of durability and longevity found in currently available combined soles is more pronounced when the combined sole is made from softer compounds or materials, such as softer EVA. Thus, while softer compounds or materials provide for better shock absorption, comfort and cushioning to the foot, the use of softer compound or materials reduces the durability and longevity of currently available combined soles.
Additionally, current shoes that are comprised of a combined sole, regardless of softness, are less durable than shoes comprised of separate midsoles and rubber outsoles.
Due to this fact, there is no material currently available for use in a sole or combined sole that is capable of providing both superior durability and softness.
To overcome this unmet need, current soles often incorporate gel and/or air compartments to create desired shock absorption, comfort and/or cushioning properties, while at the same time creating the desired level of softness. However, the use of gel and/or air pockets increase cost, complexity and weight of existing soles.
There have been many attempts at producing lighter, stronger, and more stable sole materials that also provide for more cushioning while maintaining or increasing durability. Footwear soles and processes for their manufacturing are known in the art.
For example, U.S. Pat. No. 5,560,877 titled, “PROCESS FOR MANUFACTURING AN ETHYLENE VINYL ACETATE SOLE USING FIRST AND SECOND MOLD UNITS” issued Oct. 6, 1996 discloses, “a process for manufacturing an ethylene vinyl acetate (EVA) sole that involves weighing molding compounds for manufacturing the sole. The molding compounds include, by weight, 65-75% of ethylene vinyl acetate pellets, 3-5% of blowing agents, 20-30% of fillers, and 1-2% of crosslinking agents. The molded compounds are mixed, and extruded by means of a twin screw extruder so as to form a web of unfoamed extruded output. The web is cut into sheets. At least one of the sheets is placed into a first mold unit, which is heated and pressurized so as to form a rough foamed sole. The rough foamed sole is placed into a second mold unit, which is heated, pressurized, and cooled so as to form an embossed sole with a predetermined pattern. The embossed sole is trimmed so as to form a finished ethylene vinyl acetate sole.”
In another example, U.S. Pat. No. 5,177,824 titled “METHOD OF MAKING EVA MIDSOLE” issued Jan. 12, 1993 discloses “a method of making shoe midsole includes a compound containing in percentage by weight the substances such as 100% of ethylene vinyl acetate (EVA) into which 5-40% of filling agent, 1-10% of foaming agent, 0.5-3% of bridging agent, 0.5-5% of finishing aid, 0.1-1% of foaming aid and coloring agent are added. Such compound is made into particles to be injected into the primary mold in which the preliminary blank of midsole is formed. The preliminary blank is made to foam to take shape of a molded blank under heat and pressure so as to ensure that the size of the molded blank corresponds to that of the midsole intended to be made. The molded blank is then treated in the secondary mold under heat and pressure and is subsequently cooled to take form of the midsole intended to be manufactured.”
In another example, U.S. Pat. No. 5,308,420 titled “EVA INSOLE MANUFACTURING PROCESS” issued Oct. 1, 1996 discloses “an EVA insole manufacturing process includes a step of making a molding by injecting molding an EVA resin and foaming agent mixture without through crushing or cutting procedure, and a step of heating the molding thus obtained in a mold so that it forms into a predetermined shape. Two or more moldings which respectively contain a different concentration of foaming agent or a different pigment color may be molded together so as to produce an insole which has different hardness and color at different parts thereof.”
In another example, U.S. Pat. No. 6,201,032 B1 titled “EVA-BASED FOAMABLE COMPOSITION AND PROCESS FOR MAKING BIODEGRADABLE EVA FOAM” discloses an “EVA-based foamable composition containing an EVA resin, a foaming agent, a cross-linking agent, a lubricant, a filler, and a plant material selected from a group consisting of a starchy material, powdered grain husks, and wood shavings.”
In another example, U.S. Pub. No. US 2013/0074366 A1 titled “COMPOUND STRUCTURE OF MID-SOLE AND INSOLE” discloses “a compound structure of mid-sole and insole. A PU outer sole is made into a trough shape in order to reduce the use of PU and thus the weight thereof. The mid-sole and insole are made as a compound of a lightweight material, such as EVA, and disposed inside the trough. The invention thus provides best comfort to the user while the total weight of shoe is effectively reduced.”
In another example, U.S. Pub. No. US 2005/0258560 A1 titled “METHOD FOR PRODUCING AN EVA SOLE MATERIAL” discloses a “a method for producing an EVA sole material compris[ing] the steps of uniformly mixing EVA (ethylene-vinylacetate) material and foam material sufficiently as a mixture material; using at least one rollers rolling through the mixture material as a sheet; cutting the sheet into a plurality of sub-sheets; overlapping some of the plurality of sub-sheets to have a predetermined weight; placing the overlapping sub-sheets into a sealed space in a mold having a texture of a shoe; venting and vacuuming air within the space; foaming the sub-sheets in the mold; vacuuming the sub-sheets in the mold; transferring the sub-sheets through a transfer belt with different temperature stages of 75° C., 65° C., 55° C., 35° C. sequentially through a time period of about 40 minutes; wherein each temperature being retained another predetermined time period in the transfer belt; and checking and packing the produced sub-sheets.”
In another example, U.S. Pub. No. US 2011/0252670 A1 titled, “DUAL DENSITY EVA FOOTWEAR MID-SOLE AND METHOD OF MAKING SAME” discloses “The method for fabricating a dual-density mid-sole includes the steps of: injection molding EVA material of a first density into a block; placing the first density EVA block and raw EVA material pellets of a second density together in a mold cavity; and applying heat and pressure to the first density EVA block and raw EVA material pellets of a second density in the mold cavity to form a fused component. The fused component is shaped and detailed into the mid-sole in a separate mold cavity. The result is a dual-density mid-sole consisting of one or more blocks of EVA material of a first density fused to EVA material of a second density where the size, shape and location of the different density sections can be accurately controlled and precisely defined. An article of footwear including an upper, the dual-density mid-sole consisting of one or more blocks of EVA material of a first density fused to EVA material of a second density, and an outsole, may be formed.”
There is no currently disclosed combined sole or general sole material for creating a sole component that exhibits a completely satisfactory combination of softness, resiliency, support and high durability.
It is therefore an object of embodiments herein to provide a new composition of matter and process of manufacture of said composition to be used in footwear, which exhibits the properties of low durometer softness, full support and a high resistance to wear and abrasion all in one material. Embodiments herein provide for a material that is durable, light, strong and abrasion resistant for use as a sole component and/or combined sole that also offers superior cushioning for use in shoe soles as compared to any sole material previously known.
None of the foregoing references, alone or in combination, teach the salient and essential features of embodiments disclosed herein. There remains, therefore an unmet need.